Photo by John Suchocki / The RepublicanPsychology professor Rebecca M.C. Spencer shows sensor leads used in sleep studies on older adults.AMHERST – It’s no secret that as you age, sleep often becomes more fitful, but it’s still a secret what part that may play in the reduced ability of older people to learn as readily as they could when they were younger.
Now researchers at the University of Massachusetts in Amherst, led by Rebecca M. C. Spencer, a professor of psychology, are trying to isolate the stage of sleep that boosts learning most and to discover more about the overall role sleep plays in learning.
“When you sleep, the brain replays the ‘movie’ from your day and we believe this is how sleep improves memory. As we grow old, that movie might play a bit longer, but it is also interrupted more frequently,” says Spencer, who is director of the Cognition and Action Lab at the university.
The interruptions may be events like getting up to go to the bathroom or waking up, but they may also be milder interruptions like moving from one sleep stage to another, she said. It is thought that some critical stages of sleep are being interrupted more frequently in older adults than younger adults. This suggests that it is not a change in the overall quantity of sleep that reduces the benefits sleep conveys on memory, but rather the quality of specific sleep stages that makes the difference.
Sleep researchers break up sleep into five different stages, ranging from light sleep to deeper sleep. In REM (rapid eye movement) sleep, which accounts for about 20 percent of sleep and occurs during deeper sleep, most dreaming occurs. The researchers are studying non-REM sleep during a particular stage when motor learning, the processes underlying learning to play tennis, golf or the piano, is increased.
While older adults often sleep less than when they were young, non-REM sleep is preserved and may even increase. The downside, however, is that this stage of sleep is interrupted more in older people, Spencer said.
For their study, the researchers, who include UMass graduate students in psychology, asked subjects to learn a skill such as playing the keys of a piano in a particular sequence.
“We train a subject on a task at 8 p.m. then have them recall it at 8 a.m. after sleeping. Young adults show more of a benefit of sleep in their performance. They might show a 15 percent improvement in the morning. For older adults, the speed of their movement was about the same in the morning as in the evening,” Spencer said.
She said the goal of the study is to determine the effect of interrupted non-REM sleep on learning and if there is a connection, to find a treatment for it so as to increase the ability of older people to learn.
“Is there a way to treat the fragmentation of sleep and does that improve the memory? Maybe it can be done without drugs. Maybe exercise will allow them to sleep better and improve their performance,” Spencer said.
The three-year study is being funded by a $750,000 grant from the National Institutes of Health.